/*
 * Copyright (c) 2011-2012 Alexander Dubu
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * o  Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * o  Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * o  Neither the name Axil nor the names of its contributors may be used to
 *    endorse or promote products derived from this software without specific
 *    prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

package axil.definition;

import axil.api.AxilObject;
import axil.api.AxilType;
import axil.etc.Identity;
import axil.framework.type.UnitizedType;
import axil.framework.validation.Validated;
import axil.framework.validation.ValidationContext;
import axil.framework.xml.InputXML;
import axil.stdlib.numbers.type.Decimal;
import axil.stdlib.numbers.type.Int;
import axil.stdlib.numbers.type.Num;

import java.util.List;

import static axil.framework.Functions.require;


/**
 * The definition of a single unit, such as meters or tons.
 */
public class UnitDefinition implements Validated, Identity {
	private String name;
	private String title;
	private List<String> aliases;
	private String ascii;
	private String unicode;
	private String factor;
	private Code to;
	private Code from;

	private transient Units units;
	private transient Num conversion;


	public UnitDefinition(InputXML xml) {
		name = xml.content("name");
		title = xml.content("title");
		aliases = xml.strings("aliases", "alias");
		ascii = xml.content("ascii-format", null);
		unicode = xml.content("unicode-format", null);
		factor = xml.content("conversion-factor", null);
		to = xml.object(Code.class, "to-base-unit", null);
		from = xml.object(Code.class, "from-base-unit", null);

		ascii = ascii == null ? name : ascii;
		unicode = unicode == null ? ascii : unicode;
	}

	final void link(Units units)	{
		this.units = units;
	}
	public String name() 			{
		return name;
	}
	public String title()			{
		return title;
	}
	public List<String> aliases()	{
		return aliases;
	}
	public String ascii()			{
		return ascii;
	}
	public String unicode()			{
		return unicode;
	}
	public Code to()				{
		return to;
	}
	public Code from()				{
		return from;
	}


	/**
	 * Return a string by which this object's value can be identified. The
	 * string returned cannot be null, but may be empty.
	 */
	public String identity() {
		return require(name);
	}


	public Units units() {
		assert units != null;
		return units;
	}


	/**
	 * Get the conversion factor between this unit and the base unit. The base
	 * unit is multiplied by the conversion factor to get this unit, and divided
	 * by this factor to get the base unit. A null is returned is script code is
	 * necessary to perform the conversion.
	 */
	public Num conversion() {
		if (conversion == null) {
			if (factor == null) {
				return null;
			}
			if (factor.indexOf('.') > 0) {
				conversion = Decimal.from(factor);
			} else {
				conversion = Int.from(Integer.parseInt(factor));
			}
		}
		return conversion;
	}


	/**
	 * Validate this object in the given context. Any problems detected with the
	 * correctness or completeness of this object are placed into the context.
	 * This method descends into its owned members, validating them as well.
	 */
	public void validate(ValidationContext context) {
		context.required("name", name);
		context.required("title", title);
		context.required("ascii", ascii);
	}


	/**
	 * Compress this object, reducing its memory footprint as much as possible.
	 * A compressed object is still fully functional for script evaluation but
	 * may no longer possess complete metadata.
	 */
	public void compress() {
		title = null;
	}


	/**
	 * Tell if the type for representing these units can be created from this
	 * base type. For example, "distance" would be the unitized type, and
	 * "integer" would be the base type.
	 */
	public boolean supports(AxilType base) {
		return units.supports(base);
	}


	/**
	 * Get the actual type (not the base type) used for representing objects
	 * of these units. The type returned is never null. Note that the type
	 * returned may not actually be supported for a particular compilation
	 * context.
	 */
	public AxilType type() {
		return units.type();
	}


	/**
	 * Create a new unitized object of these units with the base value. A new,
	 * non-null object is returned.
	 */
	public AxilObject from(AxilObject base) {
		return ((UnitizedType)type()).from(base, this);
	}
}
